In the US, researchers at the Massachusetts Institute of Technology (MIT) have discovered a new combination process that could increase the efficiency of coal to between 55 and 60%, “twice the fuel-to-electricity efficiency of today’s conventional coal plants,” MIT said in a news statement.
According to MIT, conventional coal-burning power plants only convert 30% of the energy contained in coal to electricity.
Through this unique find, it could halve the amount of carbon dioxide produced for producing the same amount of energy using today’s methods.
The concept involves combining into a single system two well-known technologies: coal gasification and fuel cells, proposed by MIT doctoral student Katherine Ong and Ronald C. Crane (1972) Professor Ahmed Ghoniem, which is described in their paper in the Journal of Power Sources.
MIT explained: “Coal gasification is a way of extracting burnable gaseous fuel from pulverised coal, rather than burning the coal itself.
“The technique is widely used in chemical processing plants as a way of producing hydrogen gas. Fuel cells produce electricity from a gaseous fuel by passing it through a battery-like system where the fuel reacts electrochemically with oxygen from the air.”
MIT doctoral student, Ong, explains that the two systems complement each other as both processes operate around 800oC or more.
Ong added that by combining the two in a single plant, heat would be exchanged with minimal energy loss, while at the same time the fuel cell would generate enough heat to sustain the gasification part of the process.
This process would eliminate the need for a separate heating system, which is usually provided by burning a portion of the coal.
How the process would work
Explaining the process MIT said: “The system would start with coal gasification, a process where coal is crushed to a powder and heated in a flow of hot steam that releases the gases it contains — primarily carbon monoxide and hydrogen.
After those gases are freed, Ong and Ghoniem suggest funneling them through a fuel cell where a membrane splits off the carbon monoxide and hydrogen from oxygen, thus creating electricity
“The fuel cell would, in turn, create heat that could generate more steam to continue the gasification process. This would eliminate the need to burn some of the coal to generate the higher temps at which gasification occur.”
With a pilot still needing to be developed, Ong said: “This system requires no new technologies. It’s just a matter of coupling these existing technologies together well.”